Many processes for forming Ziegler-Natta catalyst systems are known. However, few of those processes include heat treatment and such processes do not suggest that heat-treatment of catalyst intermediates (rather than preactivated catalysts) will provide any effect in polymer shear response and molecular weight distribution. Moreover, in certain cases, heat-treatment of catalyst and its intermediates can pose adverse effect on catalyst activity.
Therefore, it is desirable to develop processes for forming heat-treated Ziegler-Natta catalysts that can modify polymer shear properties and/or polymer molecular weight distribution properties without decreasing catalyst activity.